Data transmission method of frequency hopping mesh network, network node equipment and network system

Abstract

The invention discloses a data transmission method of a frequency hopping mesh network, network node equipment and a network system, and belongs to the technical field of wireless mesh networks. The data transmission method of the frequency hopping mesh network comprises the following steps: S100, constructing the frequency hopping mesh network with more than two frequencies and more than one hop; s200, executing clock synchronization operation between each child node and each father node; s300, dividing a data transmission time period of the frequency hopping mesh network into a plurality of time slots; s400, each node selects a frequency point for Rx according to the source MAC address of the data packet and the current time slot; each node selects a frequency point for Tx according to the destination MAC address of the data packet and the current time slot; wherein T < x > / R < x > stops when the current time slot is finished, and then starts in a new time slot. According to the invention, the whole effective bandwidth is fully utilized to improve the overall capacity of the mesh network, and the anti-interference performance of the network is improved.

Description

Technical Field

[0001] This invention belongs to the field of wireless mesh network technology, specifically relating to a data transmission method, network node device, and network system for a frequency-hopping mesh network. Background Technology

[0002] Mesh networks, also known as wireless mesh networks, are a type of multi-hop network, evolved from ad hoc networks, and are one of the key technologies for solving the "last mile" problem. Mesh networking requires comprehensive consideration of factors such as channel interference, hop count selection, and frequency selection. Regarding frequency selection, the main current approaches are single-band mesh networking and dual-band mesh networking, which are described below.

[0003] 1) Single-frequency mesh networking: combined with Figure 1 and Figure 2 As shown, all wireless access points (Mesh APs) and wired access points (Root APs) operate on the same frequency band for both access and backhaul. Depending on the product implementation and the channel interference environment during networking, the channels used between each hop may be completely independent and interference-free, or they may be channels with some interference (the latter is more common in real-world environments). Because of interference between adjacent nodes, all nodes cannot receive or transmit simultaneously, requiring negotiation using a CSMA / CA MAC mechanism over multiple hops. As the number of hops increases, the bandwidth allocated to each Mesh AP will decrease sharply, significantly limiting the actual performance of single-frequency networking. Figure 1 This is a schematic diagram of a single-frequency, single-hop scenario, where CH.1 and CH.6 are both channels on 2.4 GHz; Figure 2 This is a schematic diagram of a single-frequency dual-hop scenario, where CH.1, CH.6, and CH.11 are all channels on 2.4 GHz.

[0004] 2) Dual-band mesh networking: combined with Figure 3 and Figure 4As shown, in a dual-band network, each node uses two different frequency bands for backhaul and access. For example, local access services use the 2.4GHz 802.11b / g channel, while the backbone Mesh backhaul network uses the 5.8GHz 802.11a channel, eliminating interference between them. This allows each Mesh AP to perform backhaul forwarding while serving local access users. Compared to single-band networks, dual-band networking solves the channel interference problem between backhaul and access, significantly improving network performance. However, in real-world environments and large-scale networks, the use of the same frequency band between backhaul links still cannot completely guarantee zero interference between channels. Therefore, as the hop count increases, the bandwidth allocated to each Mesh AP tends to decrease, and Mesh APs farther from the Root AP will be at a channel access disadvantage. Thus, the hop count in dual-band networking should be carefully set. Figure 3 This is a schematic diagram of a dual-frequency single-hop scenario, where CH.1 is the channel on 2.4 GHz and CH.148 is the channel on 5.8 GHz. Figure 4 This is a schematic diagram of a dual-frequency dual-hop scenario, where CH.1 is a channel on 2.4 GHz, and CH.148 and CH.152 are both channels on 5.8 GHz.

[0005] Patent document CN112702727A discloses a data transmission method, device, and system for a multi-frequency wireless mesh network. The method includes, at the mesh node side, identifying the source of received data, determining the frequency band for data transmission based on the source, and forwarding the data according to the destination address of the received data based on a forwarding table for that frequency band. Each frequency band has its own forwarding table, which includes a first forwarding table for Layer 2 forwarding and a second forwarding table for determining the next hop. This allows data within the same mesh network to be forwarded independently along different paths based on different frequency bands. This patent document's technical solution is a type of dual-frequency mesh network, which also suffers from inter-channel interference. As the hop count increases, the bandwidth allocated to nodes still shows a decreasing trend, and channel access becomes increasingly disadvantageous the further away from the root node. Therefore, the hop count for network configuration should be carefully set and should not be excessive. Another issue is the different transmission distances of 2.4GHz and 5GHz; frequency switching may cause insufficient transmission distance, leading to packet loss and other problems.

[0006] Furthermore, patent document CN103857058A discloses a method for setting frequency channels in a multi-hop mesh network. The method's basic principle is as follows: Nodes A and B hop frequencies in the same sequence, such as F0, F1, F2... When node A starts transmitting data at a certain frequency, for example, F1, it maintains frequency F1 until it receives an acknowledgment packet or waits for a timeout. Similarly, when node B receives data from node A at frequency F1, and the data's destination address is node B, node B remains at F1 until the data reception is complete and an acknowledgment packet is sent back. In this patent's technical solution, all nodes hop frequencies in the same sequence F0, F1, F2... When there are many devices in the network, the probability of collisions at any given time is high. Therefore, this patent proposes adding a random delay before transmitting data to reduce the probability of collisions, but this leads to a decrease in network capacity. Summary of the Invention

[0007] This invention provides a data transmission method, network node device, and network system for frequency-hopping mesh networks, aiming to fully utilize the entire effective bandwidth to improve the overall capacity of the mesh network and enhance its anti-interference performance. This invention is achieved through the following technical solutions.

[0008] In a first aspect, the present invention provides a data transmission method for a frequency-hopping mesh network, comprising:

[0009] S100: Construct frequency-hopping mesh networks with two or more frequencies and one or more hops;

[0010] S200: Performs clock synchronization operations between child nodes and parent nodes;

[0011] S300: Divides the data transmission period of the frequency hopping mesh network into several time slots;

[0012] S400: Each node selects a frequency point for Rx based on the source MAC address of the data packet and the current time slot; each node selects a frequency point for Tx based on the destination MAC address of the data packet and the current time slot; where Tx or Rx stops at the end of the current time slot and then starts in the new time slot.

[0013] As a preferred technical solution, in step S200, each parent node periodically sends a data packet containing timestamp information. After receiving the timestamp information from the parent node, each child node updates its local time, thereby completing the clock synchronization operation between each child node and each parent node.

[0014] As a preferred technical solution, in step S200, after each child node parses the timestamp information, it compares it with the local time and maintains an offset value as a correction reference for updating the local time.

[0015] As a preferred technical solution, in step S400, within any time slot, the current node is only in a transmitting or receiving state; if the current node is in a transmitting state, the current frequency of the corresponding receiving node is calculated based on the destination MAC address of the transmitted data and the current time slot, and the frequency is switched to the current frequency of the corresponding receiving node before transmitting data; if the current node is in a receiving state, the corresponding frequency is calculated based on the current node's own MAC address and the current time slot, and the receiving state is maintained after switching to the corresponding frequency of the current node, waiting for other nodes to transmit data.

[0016] As a preferred technical solution, the step between step S300 and step S400 further includes:

[0017] S3-4: Based on different time slots, selectively control the opening and closing of communication channels between different nodes according to preset gating instructions; step S400 is executed only when communication channels between relevant nodes are allowed to communicate.

[0018] As a preferred technical solution, in step S100, when configuring the combination of receive / transmit / frequency points for each node, it is ensured that the combination of receive / transmit / frequency points for two adjacent time slots of the node is different.

[0019] As a preferred technical solution, the frequency-hopping mesh network constructed in step S100 is a four-frequency one-hop network, including communication between node 0 and node 1. The frequency modulation process of communication between node 0 and node 1 is shown in the table below:

[0020]

[0021] As a preferred technical solution, the frequency-hopping mesh network constructed in step S100 is a four-frequency two-hop network, including communication between node 0 and node 1, and communication between node 1 and nodes 11 and 12; the frequency modulation process of communication between node 0 and node 1 is shown in the table below:

[0022]

[0023] Meanwhile, the frequency hopping process for communication between node 1 and nodes 11 and 12 is shown in the table below:

[0024]

[0025] In a second aspect, the present invention also provides a network node device, characterized in that it includes a memory and a processor, the memory storing a computer program, and the processor being configured to execute the steps of the data transmission method for the frequency hopping mesh network described above.

[0026] Thirdly, the present invention also provides a multi-frequency wireless mesh network system, characterized in that the system includes at least one network node device supporting at least two frequency bands for data transmission, the network node device including a memory and a processor, the memory storing a computer program, and the processor being configured to execute the steps of the data transmission method of the frequency hopping mesh network described above.

[0027] The beneficial effects of the technical solution of the present invention include: all nodes in the existing mesh network use the same frequency hopping method. The present invention proposes a new mesh frequency hopping scheme in which each node has a frequency hopping sequence associated with its own MAC address. At the same time, it provides a mechanism that enables mutual communication even if each node has a different frequency hopping sequence. This can effectively utilize the entire available frequency band and improve the capacity and anti-interference performance of the mesh network. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a single-frequency, single-hop scenario.

[0030] Figure 2 This is a schematic diagram of a single-frequency double-hop scenario.

[0031] Figure 3 This is a schematic diagram of a dual-frequency single-hop scenario.

[0032] Figure 4 This is a schematic diagram of a dual-frequency, dual-hop scenario.

[0033] Figure 5 This is a flowchart illustrating the basic scheme of the data transmission method for frequency-hopping mesh networks provided in this embodiment of the invention.

[0034] Figure 6 This refers to the frequency-hopping mesh network constructed in step S100 of the data transmission method for the frequency-hopping mesh network provided in this embodiment of the invention.

[0035] Figure 7 This is a control flowchart of the data transmission method execution process of the frequency hopping mesh network provided in the embodiment of the present invention.

[0036] Figure 8 This is a flowchart of an optimized scheme for the data transmission method of a frequency-hopping mesh network provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the technical solution of the present invention clearer and its technical advantages more apparent, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of the present invention.

[0038] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. For ease of explanation, the orientations are defined in conjunction with the drawings. These orientation definitions are merely for the purpose of clearly describing the relative positional relationships and are not intended to limit the actual orientation of the product or device during production, use, or sale. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Moreover, in the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0039] A data transmission method, network node device, and network system for a frequency-hopping mesh network are disclosed, aiming to fully utilize the entire effective bandwidth to improve the overall capacity of the mesh network and enhance its anti-interference performance. To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of the invention will be further described in detail below with reference to the accompanying drawings.

[0040] See Figure 5 As shown, a basic embodiment of the present invention provides a data transmission method for a frequency-hopping mesh network, comprising:

[0041] S100: Construct frequency-hopping mesh networks with two or more frequencies and one or more hops;

[0042] S200: Performs clock synchronization operations between child nodes and parent nodes;

[0043] S300: Divides the data transmission period of the frequency hopping mesh network into several time slots;

[0044] S400: Each node selects a frequency point for Rx based on the source MAC address of the data packet and the current time slot; each node selects a frequency point for Tx based on the destination MAC address of the data packet and the current time slot; where Tx or Rx stops at the end of the current time slot and then starts in the new time slot.

[0045] See Figure 6 As shown, the frequency-hopping mesh network constructed in this embodiment is as follows, serving as a typical example:

[0046] 1) First level: Node 0 has no parent node; Node 0 is the parent node, and Node 1 and Node 2 are child nodes of Node 0;

[0047] 2) Second level: The parent node of node 1 is node 0; node 1 is the parent node, and nodes 11 and 12 are the child nodes of node 1.

[0048] 3) Second level: The parent node of node 2 is node 0; node 2 is the parent node, and node 21 is the child node of node 2.

[0049] 4) Fourth level: The parent node of node 11 is node 1; node 11 has no child nodes.

[0050] 4) Fourth level: The parent node of node 12 is node 1; node 12 has no child nodes.

[0051] 4) Level 4: The parent node of node 21 is node 1; node 21 has no child nodes.

[0052] Specifically, in step S200 of the data transmission method for the frequency-hopping mesh network described above, each parent node periodically sends data packets containing timestamp information. For example, each parent node periodically sends beacon packets. After receiving the timestamp information relative to the parent node, each child node updates its local time, thereby completing the clock synchronization operation between each child node and each parent node. More specifically, in step S200, after each child node parses the timestamp information, it compares it with its local time and maintains an offset value as a correction reference for updating its local time.

[0053] In step S300 of the above-described frequency-hopping mesh network data transmission method, when dividing time slots, since the time of all nodes (or node devices) in the entire mesh network is consistent after time synchronization, the time is divided into time slot units according to a predetermined method. The time slot division method can be various, such as a fixed interval of 100ms or other intervals.

[0054] Combination Figure 7As shown, in step S400 of the above frequency-hopping mesh network data transmission method, in any time slot, the current node is only in the transmitting or receiving state; if the current node is in the transmitting state, the frequency point of the corresponding receiving node is calculated according to the destination MAC address of the transmitted data and the current time slot, and the frequency is switched to the current frequency point of the corresponding receiving node before transmitting data; if the current node is in the receiving state, the frequency point is calculated according to the current node's own MAC address and the current time slot, and the receiving state is maintained after switching to the corresponding frequency point of the current node, waiting for other nodes to transmit data.

[0055] The selection of the current frequency (freq) for each device is only related to its own MAC address and current time slot (t_slot), that is:

[0056] Freq = func1(mac, t_slot), where the conversion relationship can be freely constructed, and this embodiment does not impose any restrictions.

[0057] Furthermore, to avoid conflicts, the current device is either in a transmitting or receiving state within any given time slot, i.e.:

[0058] Slot_Tx=func2(mac,t_slot).

[0059] If in transmit mode, the device calculates the current frequency of the corresponding receiver device based on the target MAC address and the current timeslot, switches to the corresponding frequency, and then transmits data. If in receive mode, the device calculates the corresponding frequency based on its own MAC address and the current timeslot, switches to the corresponding frequency, maintains receive mode, and waits for data to be transmitted from other devices.

[0060] Combination Figure 8 As shown, in a preferred embodiment, the step between step S300 and step S400 further includes:

[0061] S3-4: Based on different time slots, selectively control the opening and closing of communication channels between different nodes according to preset gating instructions; step S400 is executed only when communication channels between relevant nodes are allowed to communicate.

[0062] In conjunction with the above-mentioned channel on / off control, in order to further improve the frequency allocation efficiency and anti-interference performance, in step S100, when configuring the combination of receive / transmit / frequency points for each node, it is ensured that the combination of receive / transmit / frequency points for two adjacent time slots of the node is different.

[0063] Based on the above implementation methods, the frequency hopping process of the present invention in different application scenarios is illustrated below through specific examples:

[0064] Example 1: Suppose the frequency-hopping mesh network constructed in step S100 is a four-frequency one-hop network, including communication between node 0 and node 1. The frequency modulation process of communication between node 0 and node 1 is shown in Table 1 below:

[0065]

[0066] Table 1.

[0067] Example 2: Suppose the frequency-hopping mesh network constructed in step S100 is a four-frequency two-hop network, including communication between node 0 and node 1, and communication between node 1 and nodes 11 and 12; then the frequency modulation process for communication between node 0 and node 1 is shown in Table 2 below:

[0068]

[0069] Table 2;

[0070] Meanwhile, the frequency hopping process for communication between node 1 and nodes 11 and 12 is shown in Table 3 below:

[0071]

[0072] Table 3.

[0073] The present invention also provides a network node device, including a memory and a processor, the memory storing a computer program and the processor being configured to perform the steps of the data transmission method for the frequency hopping mesh network described above.

[0074] The present invention also provides a multi-frequency wireless mesh network system, the system comprising at least one network node device supporting at least two frequency bands for data transmission, the network node device comprising a memory and a processor, the memory storing a computer program, the processor being configured to perform the steps of the data transmission method of the frequency hopping mesh network described above.

[0075] The beneficial effects of the technical solution of the present invention include: all nodes in the existing mesh network use the same frequency hopping method. The present invention proposes a new mesh frequency hopping scheme in which each node has a frequency hopping sequence associated with its own MAC address. At the same time, it provides a mechanism that enables mutual communication even if each node has a different frequency hopping sequence. This can effectively utilize the entire available frequency band and improve the capacity and anti-interference performance of the mesh network.

[0076] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A data transmission method for a frequency-hopping mesh network, characterized in that, include: S100: Construct frequency-hopping mesh networks with two or more frequencies and one or more hops; S200: Performs clock synchronization operations between child nodes and parent nodes; S300: Divides the data transmission period of the frequency hopping mesh network into several time slots; S400: Each node selects a frequency point for Rx based on the source MAC address of the data packet and the current time slot; each node selects a frequency point for Tx based on the destination MAC address of the data packet and the current time slot; where Tx or Rx stops at the end of the current time slot and then starts in the new time slot.

2. The data transmission method for a frequency-hopping mesh network according to claim 1, characterized in that, In step S200, each parent node periodically sends a data packet containing timestamp information. After receiving the timestamp information from the parent node, each child node updates its local time, thereby completing the clock synchronization operation between each child node and each parent node.

3. The data transmission method for a frequency-hopping mesh network according to claim 2, characterized in that, In step S200, after each child node parses the timestamp information, it compares it with the local time and maintains an offset value as a correction reference for updating the local time.

4. The data transmission method for a frequency-hopping mesh network according to claim 1, characterized in that, In step S400, within any time slot, the current node is only in the sending or receiving state; If the current node is in the transmitting state, the current frequency of the corresponding receiving node is calculated based on the destination MAC address of the transmitted data and the current timeslot. The frequency is switched to the current frequency of the corresponding receiving node before transmitting the data. If the current node is in receiving mode, it calculates the corresponding frequency point based on its own MAC address and current timeslot, switches to the corresponding frequency point, maintains receiving mode, and waits for other nodes to send data.

5. The data transmission method for a frequency-hopping mesh network according to any one of claims 1-4, characterized in that, Between step S300 and step S400, the following also applies: S3-4: Based on different time slots, selectively control the opening and closing of communication channels between different nodes according to preset gating instructions; step S400 is executed only when communication channels between relevant nodes are allowed to communicate.

6. The data transmission method for a frequency-hopping mesh network according to claim 5, characterized in that, In step S100, when configuring the combination of receive / transmit / frequency points for each node, it is ensured that the combination of receive / transmit / frequency points for two adjacent time slots of the node is different.

7. The data transmission method for a frequency-hopping mesh network according to claim 6, characterized in that, The frequency-hopping mesh network constructed in step S100 is a four-frequency, one-hop network, including communication between node 0 and node 1. The frequency modulation process for communication between node 0 and node 1 is shown in the table below:

8. The data transmission method for a frequency-hopping mesh network according to claim 6, characterized in that, The frequency-hopping mesh network constructed in step S100 is a four-frequency two-hop network, including communication between node 0 and node 1, and communication between node 1 and nodes 11 and 12; the frequency modulation process for communication between node 0 and node 1 is shown in the table below: ； Meanwhile, the frequency hopping process for communication between node 1 and nodes 11 and 12 is shown in the table below:

9. A network node device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor being configured to perform the steps of the data transmission method for any one of the frequency hopping mesh networks of claims 1 to 8.

10. A network system, characterized in that, The system includes at least one network node device supporting at least two frequency bands for data transmission. The network node device includes a memory and a processor. The memory stores a computer program, and the processor is configured to perform the steps of the data transmission method of the frequency hopping mesh network according to any one of claims 1 to 8.

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